To prevent the premature detonation of an explosive, an insensitive explosive munition is used in combination with an electronic safe and arm device. An electronic safe and arm device is nonfunctional until it is armed. Two independent environmental signatures must be detected to actuate the electronic safe and arm device. For example, these signatures could be fin deployment and launch acceleration in the case of a missile, or firing setback and spin in the case of an artillery projectile.
An exploding foil initiator (EFI) is the basis of an electronic safe and arm device. The EFI consists of copper and kapton in a necked-down bridge form which is vaporized. An accelerating bullet of molten copper and kapton passes through a hole in a piece of plastic or sapphire and impacts on an insensitive type explosive. The insensitive type explosive is detonated by the shock of the impact of the copper-kapton bullet.
A conventional fire set for detonating an insensitive type explosive consists of (1) a DC-DC converter including a first transformer and a capacitor and (2) a trigger circuit including a second transformer. Arming of the fire set occurs when the capacitor is charged to a high level and firing occurs when the capacitor discharges into the foil. The DC-DC converter charges the capacitor and the separate trigger circuit causes the capacitor to discharge into the foil.
The transformers used in conventional exploding foil initiator (EFI) and exploding bridge wire (EBW) fire sets are expensive and relatively large components. Thus, a need exists in the fire set art for compact, light, and cheap transformer components.